Cary P D, Hines M L, Bradbury E M, Smith B J, Johns E W
Eur J Biochem. 1981 Nov;120(2):371-7. doi: 10.1111/j.1432-1033.1981.tb05714.x.
The class of lysine-rich histones, H1, found in most eukaryotic cells is largely replaced by another class of lysine-rich histones, H5, in avian and other erythrocytes. Erythrocytes are transcriptionally inert and this state has been attributed to the presence of H5. Although there are many sequence differences between H1 and H5 both molecules have very similar structures with three well-defined domains: a flexible basic N-terminal region, an apolar globular central region and a flexible basic C-terminal region. The lengths of the N-terminal regions are different for H1 and H5 whereas the lengths of the central and C-terminal regions are very similar. Considerable interest attaches to the findings that another type of mammalian lysine-rich histone H1(0) has an apolar region exhibiting considerable sequence homology (70%) with the central globular region of H5. The abundance of H1 in cells has been found to correlate inversely with their mitotic activities. Conformational studies using high-resolution nuclear magnetic resonance and optical spectroscopy have been made of H1 and its conformational behaviour has been compared with those of H1 and H5. H1 has been found to contain a central globular region of similar size to those found in H1 and H5. However, the conformation and stability of the globular domain of H1 are very similar to the globular region of H5 rather than H1. H1 appears to be a hybrid containing a major feature of the H5 histone. The globular regions of H1 and H5 are known to bind to a specific site on the nucleosome sealing off two turns of DNA. It is proposed that H1 binds to the same site.
在大多数真核细胞中发现的富含赖氨酸的组蛋白H1，在鸟类和其他红细胞中很大程度上被另一类富含赖氨酸的组蛋白H5所取代。红细胞在转录上是惰性的，这种状态被归因于H5的存在。尽管H1和H5之间存在许多序列差异，但这两种分子具有非常相似的结构，有三个明确的结构域：一个灵活的碱性N端区域、一个非极性球状中心区域和一个灵活的碱性C端区域。H1和H5的N端区域长度不同，而中心区域和C端区域的长度非常相似。另一种哺乳动物富含赖氨酸的组蛋白H1(0)具有一个与H5的中心球状区域表现出相当程度序列同源性（70%）的非极性区域，这一发现引起了人们极大的兴趣。已发现细胞中H1的丰度与其有丝分裂活性呈负相关。已使用高分辨率核磁共振和光谱学对H1进行了构象研究，并将其构象行为与H1和H5的构象行为进行了比较。已发现H1含有一个与H1和H5中发现的大小相似的中心球状区域。然而，H1球状结构域的构象和稳定性与H5的球状区域非常相似，而不是与H1相似。H1似乎是一种含有H5组蛋白主要特征的杂种。已知H1和H5的球状区域与核小体上的一个特定位点结合，封闭两圈DNA。有人提出H1也结合到同一个位点。
